389 research outputs found
Core Polarization and Tensor Coupling Effects on Magnetic Moments of Hypernuclei
The effects of core polarization and tensor coupling on the magnetic moments
in C, O, and Ca
-hypernuclei are studied in the Dirac equation with scalar, vector and
tensor potentials. It is found that the effect of core polarization on the
magnetic moments is suppressed by tensor coupling. The
tensor potential reduces the spin-orbit splitting of states
considerably. However, almost the same magnetic moments are obtained using the
hyperon wave function obtained via the Dirac equation either with or without
the tensor potential in the electromagnetic current vertex. The
deviations of magnetic moments for states from the Schmidt values
are found to increase with nuclear mass number.Comment: 10 pages, 2 figures, 2 table
A systematic study on the binding energy of hypernuclei
In this paper, we calculated the binding energy per baryon of the
hypernuclei systemically, using the relativistic mean field theory (RMF) in a
statistic frame. Some resemble properties are found among most of the
hypernuclei found in experiments. The data show that a hypernucleus
will be more stable, if it is composed of a hyperon adding to a
stable normal nuclear core, or a hyperon replacing a neutron in a
stable normal nuclear core. According to our calculations, existences of some
new hypernuclei are predicted under the frame of RMF.Comment: 8 pages, 6 figures, 3 table
Impurity effect of hyperon on shape-coexistence nucleus S in the energy functional based collective Hamiltonian
The non-relativistic Skyrme energy density functional (EDF) based collective
Hamiltonian, that takes into account dynamical correlations related to the
restoration of broken symmetries and fluctuations of quadrupole collective
variables, is applied to quantitatively study the impurity effect of
hyperon on the collectivity of S. Several Skyrme forces for both the
nucleon-nucleon () and -nucleon () interactions are
used. The influence of pairing strengths on the polarization effect of
hyperon is also examined. It is found that although these Skyrme
forces with different pairing strengths give somewhat different low-lying
spectra for S, all of them give similar and generally small size of
reduction effect (within 5%) on the collective properties.Comment: 8 pages, 5 figures, based on the talk presented at 18th Nuclear
Physics Workshop "Maria and Pierre Curie", 2011, Kazimierz, Polan
Antimatter production in proton-proton and heavy-ion collisions at ultrarelativistic energies
One of the striking features of particle production at high beam energies is
the near equal abundance of matter and antimatter in the central rapidity
region. In this paper we study how this symmetry is reached as the beam energy
is increased. In particular, we quantify explicitly the energy dependence of
the approach to matter/antimatter symmetry in proton-proton and in heavy-ion
collisions. Expectations are presented also for the production of more complex
forms of antimatter like antihypernuclei.Comment: 7 pages, 5 figure
Phenomenological study of light (anti)nuclei, (anti)hypertriton and di-Lambda production at RHIC
We present the production of light (anti)nuclei, (anti)hypertriton and
di-Lambda based on coalescence model in central Au+Au collisions at
. The invariant yields of \He(\Hebar),
\hypert(\hypertbar), \Hee(\Heebar) obtained is found to be consistent with the
STAR measurements. The integrated yields for di-Lambda
, and is not strongly dependent
on the parameter employed for coalescence process. Relative particle ratios of
light anti(nuclei) and (anti)hypertriton are explored, and agree with
experimental data and thermal model predictions quite well. An exponential
reducion behavior is presented for the differential invariant yields with
increased baryon number. The production rate reduces by a factor of 1692 (1285)
for each additional antinucleon (nucleon) added to antinuclei (nuclei), and the
production rate of \Libar is predicted to be which is consistent
with STAR result.Comment: 4 pages, 3 figures parallel talk delivered by L. Xue at the 14th
national conference on nuclear structure, April 12nd - 16th, 2012, Huzhou,
Chin
The Lambda-Lambda Interaction and ^{6}_{Lambda Lambda}He
An OBE potential model for the ^{1}S_0 S = -2 interaction is analyzed with
emphasis on the role of coupling between the Lambda Lambda, N Xi, and Sigma
Sigma channels. Singlet scalar exchange, an approximation to two-pion exchange,
is significant in all channels; surprisingly, the one-pion exchange component
is almost negligible. The size of the channel coupling as a function of the
overall strength of the OBE model potential is examined. Implications of the
analysis for the binding energy of ^{6}_{Lambda Lambda}He are considered; the
new experimental datum may suggest a consistency between the extracted Lambda
Lambda matrix element and the relation implied by SU(3) among OBE baryon-baryon
interactions. \\Comment: 4 pages brief report to Physical Review
Nuclei, Superheavy Nuclei and Hypermatter in a chiral SU(3)-Modell
A model based on chiral SU(3)-symmetry in nonlinear realisation is used for
the investigation of nuclei, superheavy nuclei, hypernuclei and multistrange
nuclear objects (so called MEMOs). The model works very well in the case of
nuclei and hypernuclei with one Lambda-particle and rules out MEMOs. Basic
observables which are known for nuclei and hypernuclei are reproduced
satisfactorily. The model predicts Z=120 and N=172, 184 and 198 as the next
shell closures in the region of superheavy nuclei. The calculations have been
performed in self-consistent relativistic mean field approximation assuming
spherical symmetry. The parameters were adapted to known nuclei.Comment: 19 pages, 11 figure
Strange Exotic States and Compact Stars
We discuss the possible appearance of strange exotic multi-quark states in
the interior of neutron stars and signals for the existence of strange quark
matter in the core of compact stars. We show how the in-medium properties of
possible pentaquark states are constrained by pulsar mass measurements. The
possibility of generating the observed large pulsar kick velocities by
asymmetric emission of neutrinos from strange quark matter in magnetic fields
is outlined.Comment: 10 pages, invited talk given at the International Conference on
Strangeness in Quark Matter 2006 (SQM2006), UCLA, USA, March 26-31, 2006,
Journal of Physics G in press, refs. adde
Quadrupole deformation of light hypernuclei in constrained relativistic mean field model: shape evolution and shape polarization effect of hyperon
The shapes of light normal nuclei and hypernuclei are investigated
in the deformation plane by using a newly developed
constrained relativistic mean field (RMF) model. As examples, the results of
some C, Mg, and Si nuclei are presented and discussed in details. We found that
for normal nuclei the present RMF calculations and previous Skyrme-Hartree-Fock
models predict similar trends of the shape evolution with the neutron number
increasing. But some quantitative aspects from these two approaches, such as
the depth of the minimum and the softness in the direction, differ a
lot for several nuclei. For hypernuclei, in most cases, the addition
of a hyperon alters slightly the location of the ground state minimum
towards the direction of smaller and softer in the potential
energy surface . There are three exceptions, namely,
C, C, and Si in which the
polarization effect of the additional is so strong that the shapes of
these three hypernuclei are drastically different from their corresponding core
nuclei.Comment: 11 pages, 3 figures; added references and arguments in Sections III
and IV; to be published in Phys. Rev.
hypernuclei in relativistic mean field model
We have investigated the properties of in nuclei within the
framework of relativistic mean field. The coupling constants are educed with
quark meson coupling model. There is strong attractive interaction for
-nucleus and can be bind in nuclei. The depth of
optical potential for in nuclear matter is estimated.Comment: 12 page
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